Combination tools of the type shown herein are generally known as can be seen from such U.S. Pat. Nos. 3,336,611 issued to R. Schepp et al on Aug. 22, 1967; 3,965,510 issued June 29, 1976 to Ernst; 3,452,373 issued July 1, 1969 to Vosbikian et al; and 3,932,904 issued Jan. 20, 1976 to Nilsson et al.
Some of these tools are designed for manual use while others are adapted for machine or power drive, the general construction and operation being somewhat similar. In these patents, there is an inner shaft to which a screw driver bit or drill bit is affixed. The shaft is fitted within a tubular sleeve that is retractable to a first position with the bit extending out of the sleeve and the tube is advanceable to a second position in which the bit is recessed within the sleeve. In the latter position, a socket at the free end of the sleeve may be used as a driver for a headed fastener, nut or the like.
With the sleeve in the first position, the sleeve generally is coupled to the shaft to enable the sleeve to rotate on rotation of the shaft. The means of providing the engagement and advanced position maintenance form the novel features of the tools shown by the references and the known art.
Tools of this type have special application in the concrete and masonry fastener industry where a hole is drilled in masonry and a headed anchor screw (hex or square) is driven into the drilled hole. In the use of such tools, the drilling operation releases a considerable amount of concrete dust which sould be prevented from entering the tool as much as possible. The tool must allow the ready replacement of replaceable elements such as drill bits and driving sockets, yet these elements must be held firmly in place to complete the desired operations. The tool must be capable of ready shifting between its two operating positions and must remain in the position into which it is set.